syncing audio to video with logic audio 7.0

[mewman]

I have a video done with a DV camera that has audio on it. I've imported the movie into a song and can see the thumbnails at the top of the arrange window. I've recorded an alternate audio track and want to meld it to the movie, that is, I want to replace the old sound track with a new/different one I've recorded. When I hit play back I see the movie and hear the new audio track, but when I export to movie, the original .mov file in my movies folder still plays the original audio. Any suggestions from someone with experience with audio and movies in Logic 7.0? How do I bounce them together to create a new movie?